In use, two such supporting stays are normally provided at opposite sides of a window, the track of each stay being mounted on the window frame and the bar being mounted on the window sash. The arrangement is such that as the window pivots on the stays, about either a vertical or a horizontal axis, the axis of pivoting of the window sash moves away from the window frame so that when the window is open both sides thereof are accessible from one side of the window frame.
The window sash is frictionally restrained in any angular position in which it is set. This frictional restraint may be provided partly by the friction at the pivotal connections between the various elements but is largely provided by the frictional engagement between the slider and the track.
In friction supporting stays of the kind described, particularly when used for supporting side hung windows where the weight is acting downwardly on the stay, there is a tendency for the link to flex under the weight thus causing malfunction of the window.